The present invention relates to the networking of devices, in particular to methods by which devices are addressed in a local area network.
In a communication network such as a local area network (LAN), devices communicate with each other by sending digital messages. Devices may include printers, storage units, computers, controllers, and others. A typical LAN is one conforming to Ethernet standards. See, e.g., IEEE 802.3 Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications, and related standards. When more than two devices are present, it is necessary that each device be addressable so that messages may be directed to it. A network address is commonly entered into a device during its manufacture, in particular into an interface card of the device. The address is generally unchangeable. It may be considered to be analogous to a serial number, in that at least ideally no two devices have the same address. However the uniqueness of addresses is difficult to enforce, and typically some devices somewhere will have a common address. In an Ethernet application, the network address is a 48-bit sequence which does not correspond to any name that can be readily remembered by a user. Any device on the Ethernet network that wishes to send a message to another device uses that other device's network address as the destination part of the message header.
A key process that must take place upon initial set-up of the network or upon reconfiguration is the learning of the addresses of all devices that may participate in communications. When new devices are installed on a network, it is necessary for each device, including those previously installed, to ascertain the network addresses of the devices with which it communicates. It is also highly desirable to be able to assign easily remembered names to the devices. One particular computer on the network typically begins the process by issuing a request message using a global address, or a partially global address to devices of a particular type, such as all printers or printers of a particular type. All devices that recognize that address respond giving, among other information, their network addresses. After the computer receives the network addresses of all new devices, the user of that computer then assigns names to each device. A message is sent to each new device giving its assigned name, and that name is stored in a register in the device. A translation is entered in the originating computer so that future references to a user assigned device name causes that device's network address to be entered as destination into the header of messages to that device. For subsequent operations of this address discovery process, each device returns its assigned name along with the network address.
In Ethernet networks controlled by an Apple computer, address discovery is performed by the Name Binding Protocol [G. S. Sidhu, R. F. Andrews, and A. B. Oppenheimer, “Inside Apple Talk”, Addison-Wesley, 1990, pp. 7-4 to 7-17]. Here the name includes three fields, and generic or global values are permitted in each. One field is the name itself. Another field is the device type. The final zone field is set to a null value for a simple Ethernet network. The protocol begins with a message with a global name and either global or specific type. All devices that satisfy that specification respond, giving their addresses. The next step in the process is a message to each device giving it its assigned name. That name is then entered into the memory of the device. Subsequent replies to address discovery messages include the name in addition to the address. A somewhat similar procedure is performed in networks using the Internet Protocol (IP) by the Address Resolution Protocol [S. A. Thomas, “IPng and the TCP/IP Protocols”, John Wiley & Sons, 1995, pp. 132–137]. See, e.g., D. Plummer, “An Ethernet Address Resolution Protocol,” IETF Network Working Group, RFC 826 (November 1982).
The current procedures for address administration as described above may cause difficulties, particularly for users who are not adept at computer operations. This is especially likely to be true in a home or small business environment. The user operations necessary to assign and distribute device names are difficult ones. A further problem arises when a device is moved to a different location and it is desired to change that device's name to correspond to the new location. The user must again go through the difficult procedure of name assignment. If the user neglects to do this, as is likely, then the device will retain its previous name, which may now indicate a wrong location.
An additional problem arises when network addresses are not unique. This is particularly serious in a mobile network, or when the local area network is connected to a global network, such as the Internet, where addresses are expected to be unique globally.